Not to mention that you could run 10 x 18650 @ 42v in a light IF it was designed to handle 42v. The TR-3T6 is made for 3 cells max. Comparing it to another light that can use more is just silly.
Aha 
So the the 3T6 is wired in series? What is the different with parallel and series wiring when we’re talking about flashlights? With parallell the flashlight just take as much Volt and Current it needs to run in the different modes decided by the driver, while in series the flashlight gets as much Volt as the batteries give together?
I’m kind of a noob, but i want to learn
you can have 100 of battaries im paralel, and they will still give 4,2V max all together, you just get more capacity.
if you put them in series capacity is the same as of one battery, just gives more voltage and current P=U*I
correct me if i’m wrong
Aha. So, just for fun, is it much job to make the 3t6 run parallel?
I mean, when i see the need to go for a more powerful torch, i could make this a project to convert the 3t6 to run parallel and make the runtime huge 
Running numerous cells in series is asking for trouble; you're creating a pipe bomb!
-Garry
Which batteries do you have?
With better batteries runtime increases too.
Hehe, yes, but if I made the current go parallel 
I’ve ordered the 3000mAh (2500/2600mAh) batteries. The best for its price. The runtime on High wont be much more than 1,5 hours with the best batteries i think, but if i could make the torch run parallel, i could add like 3 more batteries and make the torch go for 3 hours on high Just hypothetically speaking though…
Which batteries? Trustfire flames…?
I am sure you don’t know what is best, I unsubscribe now.
Why don't you look into a different light designed for long runtime? Does it have to be a triple XM-L? How about this one at FastTech with 3 18650's in parallel? Get some good high capacity Panasonic 3400mAh cells (or back down to 3100mAh for cost savings) and you've got some serious runtime! You also have the added benefit of using it as a USB charger and being able to charge cells in the light. A much safer alternative to a TR-3T6. Mini-review found here.
-Garry
Wow, that is a nice light! Absolutely something to think about. Thank you
Trustfire flames yes. I dont mean those batteries are the best, but at that price they were the best i could find.
Of course, if want even better batteries i have to double my costs
You're not in the US, are you? Reason being, KumaBear has some amazing deals on high quality batteries.
-Garry
Oh, yes he really has Thank you for the link! No, i live in Europe Think i would have to place an order there when i get me a flashlight
Oh, well I don't think he can ship international. You could PM him and find out for sure.
-Garry
KumaBear does not ship batteries outside of US, I checked.
I resisted posting, but you have a few choices here…
1 : you have to accept that without access to a lathe/machineshop/electronics shop, building something totally new isn’t going to be easy.
2 : quickest, easiest, safest way to long run times is accept changing batteries in the field. So carry two lights, one run time light, one edc so you can change cells. As an example…
Long run time light
http://www.cnqualitygoods.com/goods.php?id=1207
Edc
http://www.fancyflashlights.com/goods.php?id=551
Now, neither of these lights bursts the 1000 lumen bubble, but you will get more than enough light for most tasks, both use the same cells, so you have redundancy, both are well made lights.
The run time light, given access to machinery can be built to give 3000 lumen on turbo, and 3 hours at 2000 - 2500 lumen.
What you will have to accept is that for maximum run time, you have to spend on cells, the 3000mah flames will probably give 2600mah in reality. You needed 3400mah brand name cells, Panasonic’s, Samsung’s, Sanyo’s, LG’s. You don’t get owt for nowt as us northern English say.
I think you have to redefine what you need, and what you want. We’d all love a 3000 lumen torch that runs for six hours on AA cells….guess what, it don’t exist yet. 
and you won’t manage to build one out of spit and hope either.
True gords1001
I guess i’ll take your advice and stack up on batteries when going out in the field. When thinking about it, it’s actually no job to just change the batteries. Guess i got hung up on something too good to be true.
With the help and tips from you guys at this forum, i think i’ve decided to go for the Trustfire 3t6. Best light for 30 bucks i’ve read, and i’ll get some spare batteries to bring with me.
Until i’ve saved up for the TK45 with two extension tubes 8) , i’ll warm up with my in near future 3t6
there are some lights that have multiple batteries in parallel, they could be worth looking into
for example a small sun zy-t08, which isn’t really small, but it is very modable. i got it from manafont for 26.26$